53) Find the mean of the marks scored by 30 students.
Marks 10-25 25-40 40-55 55-70
70-85
85-100
2
3
7
6
6
6.
No of
Students
Answers
Answered by
1
Answer:
Class interval Mean Class Interval Frequency Deviation
10-25 17.5 2 -30
25-40 32.5 3 -15
40-55 47.5=A 7 0
55-70 62.5 6 15
70-85 77.5 6 30
85-100 92.5 6 45
Mean deviation =
6
2×(−30)+3×(−15)+6×15+6×30+6×45
=
6
−60−45+90+180+270
=72.5
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